PCT publication no. WO 03/080905A discloses an apparatus and method for producing a nanofiber web. The method comprises feeding a polymer solution to a spinning nozzle to which a high voltage is applied while compressed gas is used to envelop the polymer solution in a forwarding gas stream as it exits the nozzle, and collecting the resulting nanofiber web on a grounded suction collector.
There are several disadvantages to the process disclosed in PCT publication no. WO 03/080905A, particularly if the process is carried out on a commercial scale.
One disadvantage of the prior art is the necessity of using a quite high voltage. In order to impart electrical charge on the polymer, an electrical field of sufficient strength is needed. Due to the distances involved between the spinning nozzle and the collector, high voltage is used to maintain the electric field. An object of this invention is to lower the voltage used.
Still another disadvantage of the prior art is the coupling of the spinning nozzle to collector distance to the voltage used. During operation of the prior art process, it may be desirable to change the distance of the spinning nozzle to the collector. However, by changing that distance the electric field generated between the spinning nozzle and the collector changes. This requires changing the voltage in order to maintain the same electric field. Another objective of this invention is to decouple the spinning nozzle to collector distance from the electric field.